Electromagnetic waves are commonly used to apply energy to objects. Typically, such objects are located in a cavity configured to receive electromagnetic energy. However, because the electromagnetic field distribution may be dependent on the properties (e.g., the size of the object), location, and orientation of the object as well as characteristics of the source from which the energy is applied, it is often difficult to apply electromagnetic energy in a controllable manner. One example of an electromagnetic energy application device is a microwave oven. In a microwave oven, microwaves are used to apply electromagnetic energy from an energy source to the object through air. The electromagnetic energy is then absorbed by the object and converted to thermal energy, causing the temperature of the object to rise.